1. Field of the Invention
The present invention relates to a system for remote data collection. It also relates to a method implemented in this system and a data collection device.
2. Description of the Related Art
The collection of data from geographically scattered sites, in particular points of sale, carried out for statistical purposes takes on a considerable economic significance when it constitutes, for example, one of the links in a process for profit calculation. Such collection must be carried out under the best possible reliability conditions without, however, generating excess work, while offering great flexibility of processing in particular with regard to the type of data to be collected and to be processed.
A system for collecting statistical data is already known from the French Patent Application No. 2635626 of 18th August 1988 in the name of IMS FRANCE. However, this system has the drawback of making rational use of the server center difficult due to the fact that it is the collection devices which have control of the call times and that internal clock derivatives of these devices have already been observed.
Moreover, the problem of adapting the system exists since it is necessary to provide identification of new communication protocols.
Numerous remote information collecting systems are already known, in particular for the measurement of physical variables, or more generally of data acquired at local sites.
Thus the document IBM Technical Disclosure Bulletin (Vol. 23 No. 11 April 1981) discloses a remote collection device designed to transfer collected data at pre-determined times, via a telephone line, to a remote computer. It is stated that the time for automatic dialling can be programmed so it can be modified by the remote computer during a connection. This remote collection device includes local means of storing, monitoring and processing means and a modem.
The U.S. Pat. No. 4,713,837 (GORDON) describes a communication network between dwellings and a central communication and processing site, intended for the collection of information relating to the measurement of power, gas and water consumption. This remote collection system uses a public telephone network for the transfer of measurement data collected at the level of a local site to the central site. At the level of a dwelling unit, the various measurement data is collected via input/output channels connecting meters to a local collection unit.
The U.S. Pat. No. 4,232,295 (McCONNELL) describes a system for sampling appliances of a "juke-box" type via a telephone network. At the level of each juke-box a data collector and a modem are provided, which are arranged so as to collect and transfer data relative to the use of this appliance to a central site. In this system, it is the central site which contacts each local site by telephone and requests a transfer of stored information.
The European Patent Application 0264311 (ELF FRANCE) discloses a process for the transmission of information or measurement data from a local measuring device installed at a remote site to a central interrogation station at a central location where the data is processed, by using a public telephone network while allowing normal use of the telephone line. It includes the following stages:
transmission of a first call from the central station to the local station on line of which the bell of the called station is momentarily disabled, PA1 repetition, after a certain lapse of time, of the call by the central station, PA1 line seizure, PA1 execution of the transmission procedure. PA1 at each local site, the local collection means are arranged so as to identify and collect data originating from acquisition devices which is transmitted over a first local area network serving said local site, and include local means for storing this data, PA1 and in that moreover the central site includes means for receiving via a second network, in particular a telephone network, the data stored at each local site in the local collection means in order to be processed by the central means of monitoring and processing, each data transfer being initiated by the local collection means concerned at a moment in time which has been determined beforehand and communicated by the central means of monitoring and processing. PA1 the energy consumed by a load, PA1 the power absorbed by a load, PA1 the current intensity output to a load, or PA1 the voltage at the terminals of a load.
The International Application PCT W089/08959 (TELEMETRY RESEARCH) discloses a process for the remote collection of information originating from meters installed in dwellings, in particular power meters, by using a public telephone network. In this system there is also a central site which takes the initiative in establishing communication with the local collecting devices and carries out a sampling operation of all the local sites.
In fact, current remote collection systems have the drawback of requiring complex management of communications between the local sites and the central site. Now, the main difficulties of remote collection reside in the reliability and the availability of telecommunication media. Therefore, ill-timed or unsuccessful calls contribute to considerably lowering the efficiency and therefore the usefulness of remote collection.